One of the earliest projects I worked on during my time in the Halloran lab and at LOCI was imaging microtubules dynamics in vivo in zebrafish sensory neurons. Depicted here are two Rohon-Beard neurons, with the green comets representing the growing plus ends of microtubules. A hallmark of axons are that their microtubules are oriented with their plus ends distal, so here you can see that the majority of the comets are traveling distally, away from the cell body.